Clark and others 2007 USGS Data Series 231
Spectral Library splib06a Sample Description

(For further information on spectroscopy, see: http://speclab.cr.usgs.gov)

TITLE: Siderite HS271 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: HS271

MINERAL_TYPE: Carbonate

MINERAL: Siderite (Calcite group)

FORMULA: FeCO3

FORMULA_HTML: FeCO₃

COLLECTION_LOCALITY: Roxbury, Connecticut

ORIGINAL_DONOR: Hunt and Salisbury Collection

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Magnesite and with Rhodochrosite.

"C-7. Siderite. Roxbury, Conn. (68, hand-ground). Siderite, FeCO₃, is found in extensive sedimentary beds, frequently contaminated with clay or organic matter. It is also commonly deposited in veins by hydrothermal solutions. Both magnesium and manganese commonly substitute for the iron. This particular sample is coarsely crystalline and medium brown in color. It is high in iron, as indicated by the strong ferrous ion band near 1.1µ. It is also slightly contaminated with magnetite. Being an opaque material, the magnetite lowers the overall reflectivity of the sample, makes the carbonate bands less prominent, and causes the crossover of the spectral curves in the visible. Analysis shows that this sample contains 0.98% Mg²⁺ and 7.03% Mn⁺². However, the electronic transitions of iron dominate the spectrum to such an extent that none of the sharp features due to Mn⁺⁺ are apparent in the visible spectrum." NOTE: This a different sample number than this sample (271) but the collection locality is the same. Possibly a mislabeled sample.

Sieve interval 74 - 250µm.

Hunt, G.R., J.W. Salisbury, 1971, Visible and near-infrared spectra of minerals and rocks: II. Carbonates. Modern Geology, v. 2, p. 23-30.

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

Pure siderite
Possibly some manganoan siderite also - patterns too similar to differentiate.

Konnert, Judith and Marta Flohr, 1992, unpublished data, USGS Reston, VA.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EM(WDS), ICP(Trace), WChem

COMPOSITION_TRACE:

COMPOSITION_DISCUSSION:

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1a2a3a4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns

LIB_SPECTRA_HED:	where	Wave Range	Av_Rs_Pwr	Comment
LIB_SPECTRA:	splib04a r 4445	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib05a r 6212	0.2-3.0µm	200	g.s.=
LIB_SPECTRA:	splib06a r 20461			g.s.=
LIB_SPECTRA:	splib06a r 20472			g.s.=